SANFORD, Fla. -- A slain Florida teenager and the neighborhood watch captain who shot and killed him exchanged words before the teen punched him in the nose and began banging the man's head on the ground, according to the watch captain's account of the confrontation that led to the shooting.

The Orlando Sentinel reported that George Zimmerman told police he lost 17-year-old Trayvon Martin in the neighborhood he regularly patrolled and was walking back to his vehicle last month when the youth approached him from behind.

Because Martin was black and Zimmerman has a white father and Hispanic mother, the case has become a racial flashpoint that has civil rights leaders and others leading a series of protests in Sanford and around the country. Zimmerman said he shot Martin in self-defense and has not been arrested.

Meanwhile, Martin's parents are blaming police for leaking information about their son being suspended for marijuana and details about the fight he had with Zimmerman that portrayed the teen as the aggressor.

"They killed my son and now they're trying to kill his reputation," Fulton told reporters.

Martin was suspended by Miami-Dade County schools because traces of marijuana were found in a plastic baggie in his book bag, family spokesman Ryan Julison said. Martin was serving the suspension when he was shot Feb. 26.

The Sanford Police Department insisted there was no authorized release of the new information but acknowledged there may have been a leak. City Manager Norton Bonaparte Jr. said it would be investigated and the person responsible could be fired.

Martin family attorney Benjamin Crump said the link between the youth and marijuana should have no bearing on the probe into his shooting death. State and federal agencies are investigating, with a grand jury set to convene April 10.

"If he and his friends experimented with marijuana, that is completely irrelevant," Crump said. "What does it have to do with killing their son?"

The state Department of Juvenile Justice confirmed Monday that Martin does not have a juvenile offender record. The information came after a public records request by The Associated Press.

Despite the news of Martin's possible actions the night of the shooting, rallies demanding the arrest of the 28-year-old Zimmerman spread from Florida to Indiana.

Thousands rallied Monday on the steps of the Georgia state Capitol. The crowd chanted "I am Trayvon!" and "Arrest Zimmerman now!" The protest ended with the crowd linking hands and singing, "We Shall Overcome."

Students from Morehouse College, Spelman College and Clark Atlanta University encouraged their fellow students to talk to their lawmakers about gun laws. Students wore hoodies that said, "I am Trayvon Martin" and lofted signs reading, "Don't shoot!" and "I could be next."

"We're humans, and even more so, we're American citizens, and we have the expectation that justice will be delivered," said Ronnie Mosley, 20, a student at Morehouse who helped organize the rally.

Back in Sanford, city officials named a 23-year veteran of the police department as acting chief. The appointment of Capt. Darren Scott, who is African-American, came days after Chief Bill Lee, who is white, temporarily stepped down as the agency endured withering criticism over its handling of the case.

"I know each one of you -- and everyone watching -- would like to have a quick, positive resolution to this recent event," Scott told reporters. "I urge everyone to let the system take its course."

The Sanford City Commission held its first meeting Monday since giving Lee a no confidence vote, which led to his ouster. Martin's parents both addressed the panel, urging them to take steps to arrest Zimmerman. More than 500 people crowded into the meeting, which was moved from City Hall to the Sanford Civil Center.

"We are asking for justice," said Tracy Martin, the teenager's father.

Civil rights leader Al Sharpton warned commissioners that Sanford risked becoming a 21st century version of civil rights struggle in the South during the 1960s.

Sharpton said Martin's parents endured "insults and lies" Monday over reports that their son attacked Zimmerman.

Also Monday, an attorney for Martin's mother confirmed that she filed trademark applications for two slogans containing her son's name: "Justice for Trayvon" and "I Am Trayvon." The applications said the trademarks could be used for such things as DVDs and CDs.

The trademark attorney, Kimra Major-Morris, said in an email that Fulton wants to protect intellectual property rights for "projects that will assist other families who experience similar tragedies."